SHEET 223 -

Dicyphus () Predatory Bug

Target Pests ( vaporariorum), Tobacco whitefly (Bemisia tabaci). Dicyphus will feed on two-spotted spider ( urticae), Thrips and eggs but will not control these pests.

Plants Note: Since Dicyphus is also a feeder it should not be used on crops such as Gerbra which can be damaged. Most of the work with Dicyphus has been on crops such as , pepper and where it will not cause plant damage by plant feeding.

Description The predatory bug, Dicyphus hesperus is similar to caliginosus, which is being used in Europe to control whitefly, spider , moth eggs and . The use of Dicyphus is being studied by D. Gillespie (Agriculture and Agri-Foods Canada Research Station, Agassiz, BC). Dicyphus should not be used on its own to replace other biological control agents. It is best used along with other biological control agents in greenhouse tomato crops that have, or (because of past history) are expected to have. whitefly, , or thrips problems. • Eggs are laid inside plant tissue and are not easily seen. • Adults are slender (6mm), black and green with red eyes and can fly • Nymphs are green with red eyes

Use in Biological Control • Release Dicyphus as soon as are found, early in the season at a rate of 0.25-0.5 bugs/m2 (10 ft2) of infested area; repeat in 2-3 weeks. • Release batches of 100 adults together in one area where whitefly is present or add supplementary food (frozen moth eggs: i.e. Sitotroga sp., Ephestia sp.) to these areas weekly. • Dicyphus needs large numbers of prey (+100) to reproduce so releases should only be made in areas where pests have been detected or where supplementary food is being added. • This predator obtains water from plant feeding and can survive for long periods without food but must have food to reproduce. Feeding damage to the plant or tomato fruit is superficial and not usually noticeable unless population levels exceed 100 Dicyphus/plant. • The use of banker such as mullein ( ) and eggplant is useful for increasing Dicyphus numbers as well as monitoring for pests.

Monitoring Tips • Adults and nymphs move quickly and hide in plant material when approached. • On mature tomato plants adults and nymphs are often found on the middle SHEET 223 - DICYPHUS

Life Cycle • Development from egg to adult takes 5 weeks at 25°C and 8 weeks at 20°C. • Adult females lay 3 eggs per day, for a total of 88 eggs over a 20-30 days. Eggs are laid in the tissue of plant stems and veins and hatch in 2 weeks. Using Pesticides • Spreader-stickers, insecticidal oils and soaps are harmful to predators contacted by the spray, but have little residual activity. • Most pesticides used for whitefly including systemic pesticides are harmful to Dicyphus. Check with supplier or with a chemical effect list before using any pesticide. The pesticide effects on Dicyphus are similar to spp.